We've all probably heard that Craig Barret got down on his knees and pleaded for forgiveness after Intel announced it will not be releasing a 4GHz Pentium 4. AMD must have thought that was pretty funny, as the architecture that was said to scale upwards of 5GHz didn’t even get to 4GHz, but maybe the idea of Intel’s CEO on his knees was enough for them, I’m afraid we’ll never know. We’ll also never know whether the 4GHz would have been the pinnacle of performance on introduction, but will we? Well, getting a Pentium 4 processor to 4GHz is actually a lot easier than getting Craig Barret on his knees; it just takes a bit of effort. With the 600 series processors we evaluated a few days ago that effort simply meant upping the clocks to 4GHz, there really was nothing to it. So we’ll go ahead and answer that question for you; how exactly does a 4GHz Pentium 4 stack up to AMD’s flagship Athlon 64 FX55 on the PCIe platform?

To gauge the performance of a 4GHz Pentium 4 we opted to use the Pentium 4 660 processor we evaluated earlier this week and clock it up 4GHz on the Intel 925XE chipset motherboard. Because it is multiplier locked at 18x this means running it at a mere 11% higher clock by upping the front side bus to 222MHz. To make this a fair comparison we’ll use identical parts on both systems as far as possible, as the Athlon 64 FX55 undoubtedly will not fit the LGA775 socket and vice versa. We equipped both systems with a Hitachi 7K250 250GB, Serial-Ata harddisk, and a GeForce 6800 Ultra PCIe graphic card. The Pentium 4 processor was served by 1GB of OCZ PC4300, cas 4-4-4-11 DDR2 memory on the i925XE chipset, whereas the Athlon 64 exchanged bits with the Nforce 4 SLI chipset and 1GB of OCZ DDR400, cas 2-2-2-5 memory. Naturally Windows XP SP2 was used and all the latest WHQL drivers.

The Pentium 4 660 at 5.2GHz, only at this clock speed the Athlon 64 FX was defeated.

We used Futuremark’s PCmark04 v1.30, 3Dmark03 v3.60 and 3Dmark05 v1.20 to get an impression of the performance offered and rounded our benchmarks off with compressing files with WinRAR, encoding an audio CD to MP3 and a handful of game benchmarks. The games we looked at in particular are Valve’s CS:Source and HalfLife 2, id software’s Doom3 and Ubisoft’s FarCry. All of these games were run with maximum eye candy, thus with anti aliasing set to 4x and anisotropic filtering to 8x at a 1600x1200 resolution, as we never said we’d go easy on either processor. So without further ado let’s see which processor brings the other one down to its knees, like Craig Barret, begging for forgiveness after being beat in the MHz arena.

Upon looking at the benchmarks it is clear that the 4GHz Pentium 4 is no match for AMD’s Athlon 64 FX55, the HalfLife 2 benchmark scores are particularly humiliating. But like Craig Barret we’re true boy scouts and don’t give up at the first sign of trouble. So how about we whip out some more aggressive cooling, phase change to be exact, and see how far we can push that Pentium 4 600 series processor? Let’s go find out what clock speed is needed to have that Athlon 64 FX bite the dust. We’ll start off at a mere 4.8GHz at a 266MHz front side bus and gradually raise it until we match the performance of the Athlon 64 FX55, or end up with a smoking heap of silicon, whichever comes first.

Not surprising the Pentium 4 needs quite a boost in clock speed before it is able to convincingly beat the Athlon 64 FX55, at a clock speed of no less than 5.2GHz there’s no doubt about who takes the performance crown. And yes, that’s double the clock speed of the Athlon 64 FX55 processor which runs at a mere 2.6GHz. It has to be said though that reaching a 5.2GHz clock speed isn’t for the faint of heart; the motherboard chipset and memory run at their highest supported voltages and are cooled by a plethora of fans to keep them cool. The processor, running at maximum core voltage, is interfaced with the receiving end of a 1/2 hp compressor which releases high pressure R507 gas in the evaporator bringing the temperature down to a freezing -40 degrees Celsius.

So we hope our findings put an end to all of the discussion about who’s got the fastest processor on the market, that processor is none other than AMD’s Athlon 64 FX55. Due to diminishing returns the Pentium 4 processor needs a whopping 5.2GHz clock speed to keep up with AMD’s flagship processor. So was it a good decision on Intel’s part to announce it will not be shipping a 4GHz processor? We think so, as the Pentium 4 was just never going to best AMD’s Athlon 64. Craig Barret clearly had guts and vision when making that decision, or, and that’s just as likely, he knew the 4GHz Pentium 4 needed another 1.2GHz to soundly beat AMD’s fastest, and that just wasn’t feasible.

Sander Sassen.

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